Image magnification devices of the type to which the present invention relates employ elongated optical carrier strands, such as optical fibers, for expanding the separation between adjacent portions or "pixels" of an input image, while preserving the relative positional relationships between them. Input ends of the strands are gathered together in close proximity at an input surface and illuminated by respective portions of the input object or image. The light information is then conveyed for display to output ends of the same strands similarly grouped together at an output surface, but with much greater separations. Such devices find use, for example, as large television and advertising image display screens. See, e.g., U.S. Pat. Nos. 4,090,104 and 5,184,253. Conventional devices are, however, subject to illumination intensity and image definition problems due to loss of portions of the input image falling between the input ends of adjacent fibers, and are also subject to undesirable distortions due to inaccuracies in one-to-one correspondence between input and output surfaces.
Prior attempts at fiber optic screen manufacturing methods have been labor intensive and imprecise. Most such methods involve the use of pre-drilled or slotted black plexiglass panels to space thousands of fiber optic element output ends in a linear dot matrix pattern output surface in correspondence with a tighter matrix pattern formed by the input ends. Examples of such systems are found in U.S. Pat. Nos. 3,404,000, 3,853,658 and 4,090,104. The few inventors known to be experimenting with automating this task require the simultaneous use of multiple fiber optic strands and a resulting screen configuration consisting of multiple angularly cut wedge-shaped modules using geometrically square packing of the fibers both in the input bundle and output screen faces. Such wedge-shaped modules are cumbersome to stack on top of each other and the linear packing of fibers is space inefficient and non-uniform, resulting in a high degree of light loss and incoherence in the image being presented on the output screen. The multiple angularly cut modules also cause line and patchwork patterns which further distort the images being displayed on the screen.
The use of fiber optics for image guides has been known for decades. Coherent fiber optic image guides have been manufactured using various tools commonly employed in the endoscope and baroscope industry. These manufacturing techniques include various forms of winding devices in conjunction with clamping, spooling and epoxying systems. Examples of the same are found in U.S. Pat. Nos. 3,033,731; 3,104,191; 3,373,006; 3,383,192; 3,588,221; 3,592,398; 3,871,591 and 3,989,578.
Hicks, Jr. discloses an apparatus for fiber optic image magnification in U.S. Pat. No. 3,043,910. Several companies and inventors have experimented with fabricating the Hicks display device with only limited success. Due to the costs and inaccuracies in manufacture of these devices, the market for such display screens has been limited to just a few locations, such as amusement parks and public areas like Disneyland and airport locations. These screens have operated with very marginal success.
In U.S. Pat. Nos. 4,116,739 and 4,208,096, Glenn discloses an automated method of manufacturing multiple display screens of the Hicks design by wrapping a plurality of optical fibers about successive layers of spacer elements, which are later angularly severed to create several wedge-shaped devices. Similarly constructed wedge-shaped devices are disclosed by Sedlmayr in U.S. Pat. No. 4,650,280, wherein the spacer design is altered by providing a channel-shaped lip or flange to guide a ribbon, consisting of a plurality of side-by-side adjacently lying optical fibers, onto the spacer. In U.S. Pat. Nos. 4,773,730 and 4,786,139, Sedlmayr discloses a rather complicated and cumbersome assembly arrangement of piecing together multiple wedge-shaped modular fiber display screen devices with the use of many fastening items to form a single large screen. In U.S. Pat. No. 4,867,530, Sedlmayr further discloses a slotted alteration to his previously disclosed spacer design and shows its use in assembling a screen configuration utilizing a series of modular wedge-shaped devices. The concept of using a modular block design to construct large screens by combining multiple smaller display screens and input bundles is generally known. A manually constructed fiber optic display screen of approximately 10 ft. high.times.50 ft. long consisting of dozens of modular blocks has been on display at the Disneyland Hotel in Anaheim, Calif. for more than 10 years.
The use of continuously wrapped multiple ribbons of fibers in creating these devices is subject to problems with the fibers crossing over each other during manufacture and to problems with the alignment and separation of the fibers in the output display face in order to achieve the desired magnification over the input. Past alignment attempts are shown in James U.S. Pat. No. 3,644,922, which uses notched spacers to hold the order of the fibers during placement. Sedlmayr uses channel-shaped or slotted flanges or lips molded into the spacers to receive the entire ribbon of fibers laying side by side. These methods are crude for they are either manually accomplished or incapable of precisely ordering and controlling the magnification level in the output. These methods also result in inaccuracy problems created by the linear ordering of fibers, with their center points one on top of the other in the input bundles. The fibers linearly aligned in a later row have a tendency to roll over and lay between the center points of the fibers of an earlier row. This often creates a significant disparity between alignment of the adjacent ends of the fibers in the input bundle and those of the same fibers in the output screen face, with a resulting deviation or skewing of the image on the display screen.